Somatosensation: Touch, Pain, Temperature - Anatomy and Physiology
- Which receptors detect deep pressure and high-frequency vibration?
- Lamellated (Pacinian) corpuscles, which are rapidly adapting and lie deep in the dermis and hypodermis.
- A patient with myocardial ischemia reports pain. Where is this pain commonly referred?
- To the left arm, shoulder, chest wall or jaw, which share spinal segments (about T1 to T4) with the heart.
- What is the difference between phasic and tonic receptors?
- Phasic receptors adapt quickly and signal changes in a stimulus; tonic receptors adapt slowly and signal a sustained stimulus.
- Which slowly adapting receptors in the basal epidermis signal sustained light touch and texture?
- Tactile (Merkel) discs, formed by Merkel cells and their nerve endings.
- Which receptors detect light touch in hairless skin and lie in the dermal papillae?
- Tactile (Meissner) corpuscles, which are rapidly adapting.
- Which receptor type detects pain and most temperature changes?
- Free nerve endings, which serve as nociceptors and thermoreceptors.
- Which slowly adapting receptors in the dermis respond to skin stretch?
- Bulbous (Ruffini) endings.
- Which fibers carry fast, sharp pain, and which carry slow, dull, burning pain?
- Fast sharp pain: thinly myelinated A-delta fibers. Slow burning pain: unmyelinated C fibers.
- What is referred pain?
- Visceral pain perceived at a skin region, because both share spinal cord segments that converge on the same neurons.
- Why is two-point discrimination finest on the fingertips and lips?
- These areas have a high density of receptors with small receptive fields.
- What is a receptive field of a sensory neuron?
- The area of skin whose stimulation changes that neuron's activity. Smaller fields allow finer localization.
- What is a receptor (generator) potential?
- A graded depolarization of a sensory ending whose size varies with stimulus strength; large enough ones trigger action potentials.